Causes of Proteinuria

CONTENT SUMMARY:

In the second blog post of our series about proteinuria, we will examine proteinuria causes, including: 

• Primary causes
• Secondary causes
• Medications and toxins
• Infections and inflammation
• Heredity and genetic factors 
• Lifestyle and diet
• Physical injury and trauma
• Pregnancy
• Rare and uncommon causes
• Kidney stones and obstruction
• Aging
• Diagnosis and evaluation
• Variation of treatment plans
• How to prioritize your kidney health 

This FKP Kidney Health blog will highlight the many different causes of 

proteinuria. When there’s a disturbance in your kidney function as indicated by excess protein in your urine, identifying the cause—whether that cause is deemed harmless or serious—is crucial so these dynamic, blood-cleansing organs can fulfill their duties as efficiently as possible.

CAUSES OF PROTEINURIA

• Proteinuria Unveiled: Understanding the Causes

               When high levels of protein are detected in your urine, this indicates a condition called proteinuria. Kidney patients should understand the causes of proteinuria so they can take a proactive approach to their kidney health and achieve the best possible outcome.

               Dehydration or vigorous exercise can cause proteinuria, and in this case, it’s usually not a serious concern. More serious causes of proteinuria include kidney disease, an immune disorder, diabetes, or hypertension, just to name a few. A thorough evaluation by your trusted healthcare provider or nephrologist can pinpoint what’s causing high levels of protein in your urine, which can lead to an accurate diagnosis and prompt, personalized treatment.

• Primary Causes: Glomerular Diseases

Two primary glomerular diseases are commonly identified as the leading causes of proteinuria. These diseases are glomerulonephritis and nephrotic syndrome. 

Glomerulonephritis is a condition that can develop suddenly or over time. It affects the part of the kidney called the glomerulus, which is responsible for filtering toxins, metabolic wastes, and excess fluids from the body. The buildup of these substances can cause symptoms such as fatigue and swelling because the glomerulus is inflamed and/or damaged.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIH) defines nephrotic syndrome as “a group of symptoms that indicate your kidneys are not working properly.” In addition to proteinuria, symptoms of nephrotic syndrome include low levels of protein in your blood (hypoalbuminemia), swelling in other parts of your body (edema), and high cholesterol levels and other lipids in your blood (hyperlipidemia).

• Secondary Causes: Systemic Conditions

Systemic conditions are also among the most common proteinuria causes. Two systemic 

conditions related to proteinuria include diabetes and high blood pressure. Both conditions can lead to proteinuria because they impair the glomerular filtration process by compromising the glomerulus’s overall function. 

For diabetes patients, high blood sugar levels can damage the tiny blood vessels found within your kidneys. Individuals diagnosed with high blood pressure should be aware that the excessive force exerted on blood vessels as part of this diagnosis can cause structural damage to the kidneys. 

• Medications and Toxins: Potential Triggers

Medications that you take and toxins you’re exposed to can both be potential

triggers of proteinuria. Cleveland Clinic states that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause proteinuria, and their website goes on to list the most common NSAIDs as aspirin (Bayer®), ibuprofen (Advil®), and naproxen (Aleve®). 

Regarding toxins, exposure to heavy metals such as mercury, lead, and cadmium can cause proteinuria because these toxins are capable of harming the delicate cells that make up the glomeruli. Other toxins, such as industrial chemicals and solvents, might also play a part in triggering the development of proteinuria. 

• Infections and Inflammation: Their Impact on the Kidneys

When your body is trying to fight off an infection and/or inflammation, your 

kidneys become a vital part of your immune system’s response. Defending your body against infection and inflammation makes your kidneys vulnerable because the intricate nature of the inflammatory response can inadvertently damage them. Examples of infections and inflammatory conditions that can harm your kidneys include urinary tract infections, lupus, and vasculitis.

For as resilient and powerful as your kidneys are, they’re also quite delicate; if your kidneys are damaged due to prolonged or severe infection or inflammation, their filtration process can be disrupted and result in their inability to retain essential proteins. This is why infections and inflammation are listed among the causes of proteinuria. When infections and inflammation affect the glomeruli, your kidneys’ filtration barrier becomes permeable and that’s when proteins begin to appear in your urine, raising a cause for concern. 

• Heredity and Genetic Factors

When trying to determine what causes proteinuria in urine, doctors must consider 

heredity and genetic factors as well. Individuals who have been diagnosed with genetic kidney disorders such as Alport syndrome, polycystic kidney disease, and congenital nephrotic syndrome are at greater risk of developing proteinuria. These disorders are characterized by mutations in genes that are essential for the proper functioning of your kidneys. Those who are susceptible to developing diabetes or hypertension are also at greater risk of having excess protein in their urine. 

While heredity and genetic factors are certainly acknowledged as proteinuria causes, it’s important to note that not everyone with a genetic predisposition will develop this condition. Still, this gives you all the more reason to be aware of your family’s health history and genetic risk factors so you can share this pertinent information with your doctor.

• Lifestyle and Diet: How Choices Affect Kidney Health

Proteinuria can develop on account of poor dietary choices, smoking tobacco, and alcohol consumption. These lifestyle factors all affect how your kidneys function. 

Those with diets high in sodium can develop hypertension, which is one of the causes of proteinuria. A protein-rich diet, especially one that features the regular consumption of processed meats, can also put excess strain on your kidneys. This may damage the glomerular and lead to proteinuria. Also, diets high in refined sugars and unhealthy fats can contribute to insulin resistance and an increased risk of developing Type 2 diabetes. Remember, diabetes is one of the leading systemic conditions associated with proteinuria.

Smokers harm their kidneys because tobacco constricts the blood vessels, including the ones located in the kidneys. Increased oxidative stress caused by the harmful substances found in cigarettes and other tobacco products can cause atherosclerosis, which reduces blood flow to the kidneys and causes inflammation. Damage and a potential case of proteinuria can result.

Regarding alcohol consumption, alcohol can induce dehydration, and dehydration may lead to an increased concentration of protein in the urine. When your kidneys struggle to effectively filter waste and regulate fluid balance, they may experience inflammation and incur damage; this increases your risk of proteinuria. 

It’s reassuring to know that you can make smart diet and lifestyle choices that can positively affect the health of your kidneys. By not smoking, moderating your alcohol intake, maintaining a healthy diet, exercising regularly, and attending regular check-ups with your nephrologist or healthcare provider, you can do your part to lower your risk of developing proteinuria. 

• Physical Injury and Trauma: Unexpected Causes

The National Library of Medicine has published studies relating to how trauma and injury can cause proteinuria. The first of these articles is titled “Proteinuria following trauma,” and the second is titled “Proteinuria after burn injury.” Both articles reference studies conducted on trauma patients and burn victims, making it clear that there is a correlation between proteinuria, physical injury, and trauma.

If you sustain an injury or trauma, keep in mind that your doctor may try to determine if you have protein in your urine. Acute proteinuria—meaning that there’s a sudden increase in protein in the urine—will need to be monitored during your recovery. 

• Pregnancy-Related Proteinuria

If you are pregnant or planning to become pregnant, it’s important to understand how and why you might be diagnosed with pregnancy-related proteinuria, and what that means for the health of you and your baby. 

Women with chronic kidney disease or other pre-existing kidney conditions could be at an increased risk of developing proteinuria during pregnancy. Pregnancy transforms your body in numerous ways and places extra strain on your organs as the baby grows and develops. The kidneys are no exception.

Elevated levels of protein during the first 20 weeks of pregnancy usually indicate an underlying condition such as diabetes, lupus, and chronic kidney disease. If you have proteinuria later in pregnancy—specifically, after the 20 week-mark—this could be a symptom of preeclampsia or gestational hypertension. 

Your doctor will regularly test your urine to check for proteinuria. If you are diagnosed with this condition, you are at risk of developing preeclampsia. A research article published by the National Library of Medicine defines preeclampsia as “a pregnancy-specific hypertensive disorder that may lead to serious maternal and fetal complications. It is a multisystem disease that is commonly, but not always, accompanied by proteinuria.” Preeclampsia can result in serious complications for you and your baby. Those complications include organ damage/failure, strokes, pregnancy loss, and preterm birth. If you are diagnosed with proteinuria during pregnancy, your doctor will monitor and treat the condition based on its severity, your age, and other factors. 

Proteinuria during pregnancy could also indicate gestational hypertension. Gestational hypertension means that you have high blood pressure. This is a cause for concern because this condition may go on to indicate preeclampsia. Your proteinuria as it relates to gestational hypertension will need to be addressed by your doctor. 

It’s also worth noting that pregnancy can increase the frequency of urinary tract infections (UTIs) among some women. American Pregnancy Association writes, “Pregnant women are at increased risk for UTIs starting in week 6 through week 24 because of changes in the urinary tract. The uterus sits directly on top of the bladder. As the uterus grows, its increased weight can block the drainage of urine from the bladder, causing a urinary tract infection during pregnancy.” If you have a UTI or if you are simply dehydrated, urinary protein may be detected in your urine. Those protein levels should return to normal as those issues get resolved. If they don’t, your doctor may recommend further testing.

• Rare and Uncommon Causes of Proteinuria

There are some rare and uncommon proteinuria causes that you should be aware of as 

part of your kidney health. Doctors and researchers have noticed that certain autoimmune diseases and blood disorders can cause excess urinary protein. 

Autoimmune diseases that may cause proteinuria include systemic lupus and Goodpasture Syndrome. Systemic lupus causes inflammation within the kidneys, while Goodpasture Syndrome involves the immune system attacking tissues located in your kidneys and lungs. Because both autoimmune diseases lower overall kidney function, proteinuria may develop. 

Blood disorders that cause proteinuria include amyloidosis and Hemolytic Uremic 

Syndrome. Amyloidosis occurs when abnormal proteins build up in organs. These abnormal proteins, called amyloids, can appear within the kidneys and negate their effectiveness. 

Meanwhile, Hemolytic Uremic Syndrome damages the tiny blood vessels in the kidneys and, again, increases the chance of dysfunction. Any time kidney function is compromised, excess protein can leak into the urine.

A rare blood cancer called plasma cell cancer can also cause proteinuria. Cleveland Clinic writes, “Multiple myeloma happens when healthy cells turn into abnormal cells that multiply and produce abnormal antibodies called M proteins. This change starts a cascade of medical issues and conditions that can affect your bones, your kidneys and your body’s ability to make healthy white and red blood cells and platelets.” This article further notes that “abnormal plasma cells make M proteins that block the filtering process and damage your kidneys.” When your kidneys are damaged, your doctor and care team need to make a plan to prevent further damage.

• Kidney Stones and Obstruction: A Potential Trigger

Another potential trigger of proteinuria? Kidney stones and obstruction. 

Kidney stones are hard deposits made of minerals and salts that form inside your 

kidneys, according to Mayo Clinic. Mayo Clinic’s website on this subject notes that “diet, excess body weight, some medical conditions, and certain supplements and medications are among the many causes of kidney stones. Kidney stones can affect any part of your urinary tract— from your kidneys to your bladder.” Kidney stones can cause proteinuria because they disrupt the normal flow of urine. The increased pressure on your kidneys can cause irritation and inflammation within the renal tubules that filter proteins. If these tubules get damaged, excess protein can leak into the urine. Proteinuria brought on by kidney stones is mostly regarded as a temporary issue because the proteinuria tends to resolve once that kidney stone passes.  

Urinary tract obstructions are similar to kidney stones in that they impair the natural flow of urine and place excess strain on your kidneys. Any time increased pressure is placed on your kidneys, their delicate structures may become damaged and cause proteinuria in urine. Urinary tract obstructions can be caused by prostate enlargement, a tumor, an infection, blood clots, and other issues. University of Iowa Hospitals and Clinics has published an extensive list of urinary tract obstructions and advises that urinary tract obstructions be evaluated right away.

• The Role of Aging: Age-Related Proteinuria

Aging certainly comes with its perks and its pleasures, but when it comes to kidney 

health, aging can cause your kidneys to undergo changes that may warrant you and your doctor’s close attention. Remember, your kidneys are vital organs that are responsible for filtering waste and maintaining fluid balance. It’s important to prioritize the health of your kidneys and other vital organs as you get older.

One of the most common age-related causes of proteinuria in older adults has a lot to do with the nephrons within your kidneys. The number of filtering units that you have will decrease with age, which can lead to structural changes within the renal tissue. If your kidneys aren’t filtering substances as well as they used to—and they’re not reabsorbing the proteins in your blood as expected—then you might be diagnosed with proteinuria. 

As you age, you become more and more susceptible to being diagnosed with chronic conditions such as high blood pressure, diabetes, and cardiovascular disease. These and other conditions can compromise your kidney health and cause proteinuria. The same can be said about certain medications you may have to take to treat these conditions. 

If you have been diagnosed with a chronic condition such as diabetes, it would behoove you to speak with your doctor about undergoing regular health screenings that monitor how well your kidneys are working. Early detection often makes chronic kidney disease and other kidney-related issues easier to manage, per American Family Physician. Understanding what causes proteinuria in urine can empower you to take steps toward prevention and early intervention of an underlying chronic kidney condition or another serious health issue. 

• Diagnosis and Evaluation: Identifying the Root Cause

In the early stages of proteinuria, you may not have any symptoms. However, as the 

condition progresses, you could experience symptoms such as swelling in your face, belly, feet, or ankles; shortness of breath; tiredness; muscle cramping at night; lack of appetite; and/or foamy or bubbly urine. You know your body best. If something doesn’t feel right, contact your doctor right away. 

If your doctor suspects that you may have proteinuria, a comprehensive evaluation and diagnostic testing will be in order. During your evaluation, you’ll be asked to share your medical history and your family’s medical history, plus any recent developments relating to those topics. Your doctor will also closely review your current and past medications, including over-the-counter drugs and herbal supplements you are taking or have taken in the past. Be sure to tell your doctor if you were on certain medications for an extended period of time.

Other topics your doctor will discuss will likely include your exposure to toxins, your diet and lifestyle habits, physical injuries or trauma you may have experienced, and other proteinuria causes that we’ve listed above. 

Your doctor’s goal will be to conduct a thorough evaluation that will help accurately identify the root cause of your proteinuria. They’ll check your blood pressure, look for signs of swelling, and examine your body to determine if you have signs of an underlying autoimmune disorder such as systemic lupus, which, in some people, can produce a butterfly-shaped rash that appears across the nose and cheeks.

A urine analysis—aptly called a urinalysis—will confirm the presence of excess urinary protein and provide further insights about the potential cause of your underlying condition. The urinalysis will reveal the severity of proteinuria by quantifying the amount and identifying if your proteinuria diagnosis should be classified as mild, moderate, or severe.

In “Proteinuria in Adults: A Diagnostic Approach” by American Family Physician, the authors mention that there are three pathophysiologic mechanisms of proteinuria: glomerular, tubular, or overflow. They define glomerular as “the most common cause of pathologic proteinuria.” Once your proteinuria is classified accordingly, your doctor will review the urinalysis for other abnormalities in your urine, such as the presence of red blood cells, white blood cells, or granular casts. These findings can provide additional clues about the underlying cause of proteinuria in urine and help your doctor confirm your diagnosis.

The urinalysis is a valuable test when it comes to proteinuria. It’s this test that will likely result in you having to undergo other diagnostic tests (blood tests and/or imaging tests, for example). All of these tests will allow your doctor to better pinpoint why you have excess protein in your urine. 

It’s worth noting that a kidney biopsy may be necessary to make a definitive diagnosis. Your doctor will share more information with you about this test if it’s recommended to you. 

By determining the specific cause of proteinuria, you and your doctor can move 

forward with a customized treatment plan that will prioritize your kidney health. 

• Understanding the Impact: How Different Causes Affect Treatment

If you have been diagnosed with proteinuria, keep in mind that your treatment 

plan will be tailored specifically to address the underlying condition that you have. If you are a woman who is 30 weeks pregnant, for example, treatment for the underlying cause of proteinuria—which could be preeclampsia—will look much different than a treatment plan created for a 55-year-old man with diabetes and hypertension. 

Your care team must accurately diagnose the underlying cause of your proteinuria and then consider the best and most effective ways it can be treated. Talk to your doctor openly and honestly about your concerns, and ask as many questions you may have; it’s important that you feel comfortable with your treatment plan and understand how to proceed with it, keeping in mind that your underlying cause of proteinuria is unique to you and needs to be addressed as such. 

• Conclusion: Empowering Kidney Patients with Knowledge

What causes proteinuria in urine? Causes include glomerular diseases, systemic 

conditions, infections and inflammation, toxins and medications, heredity and genetic factors, lifestyle and diet, physical injury and trauma, pregnancy, kidney stones and obstructions, aging, and even rare and uncommon causes such as autoimmune diseases, blood disorders, and plasma cell cancer. 

If urinary protein has been detected in your urine, treat it as a cause for concern because it may very well indicate an underlying condition that can affect your overall health and well-being. 

This blog has focused on what causes proteinuria, and we hope that it has given you 

valuable insights about this condition. Knowledge is power, as they say, and the more you understand proteinuria causes, the more you can feel in control of your health—especially your kidney health. 

Your kidneys are rather small, but they’re incredibly vital organs. In addition to filtering impurities from your blood, regulating your blood pressure, and balancing fluids and electrolytes, your kidneys work in concert with other organs to maintain the stability of other systems in your body, including the cardiovascular system and endocrine system. That said, if you’re worried that you may have symptoms of proteinuria, or that you might be at risk of developing it, seek support and guidance from your doctor.

Thank you for reading about what causes proteinuria in urine on the FKP Kidney Health blog. We hope you’ll bookmark this blog and view it as a valuable resource, and that you’ll consider sharing it with others who may benefit from learning about all the various causes of proteinuria.